In this study, we report the synthesis of ultrasmall NiMo bimetallic metal oxide nanoclusters (similar to 2 nm), supported on gamma-Al2O3 for hydrodesulfurization reaction. The metal oxide nanoclusters were prepared by colloidal synthesis using oleic acid and oleylamine as ligands, followed by incorporation of nanoclusters into the pores of gamma-Al2O3. The nanocluster supported gamma-Al2O3 was calcined to remove the ligands followed by sulfidation. Compared to the catalyst prepared using conventional wet impregnation method, the nanoclusters prepared using colloidal synthesis showed enhanced catalytic activity for the hydrodesulfurization of dibenzothiophene because of the ultrasmall size of the metal oxide nanoclusters supported on gamma-Al2O3. In addition, we have evaluated the performance of our catalyst with a diesel sample (containing similar to 14,700 ppm sulfur) obtained from a crude distillation unit. The sulfur content of the feed was reduced to similar to 35 ppm at 335 degrees C and LHSV 2 h(-1) showing the good catalytic activity. (C) 2015 Elsevier B.V. All rights reserved.